This invention relates to a magnetic recording unit used as an external recording unit for a computer or the like, and more particularly to a magnetic head slider which is suitable for enhancing the sliding durability of a recording-reproducing element portion and a slider, having this element portion mounted thereon, and also is suitable for enhancing the recording density.
As disclosed in Japanese Patent Unexamined Publication No. 2-103714, in a conventional magnetic head slider, a recording-reproducing element portion has an alumina film which is formed as a base film for forming and holding magnetic poles, a coil, a magneto-resistance effect element and so on, or as a protective film which is effective in an element-forming process so that the magnetic poles, the coil, the magneto-resistance effect element and so on will not be damaged during process steps and during handling. As described in the above publication, this alumina film can be relatively easily worn and damaged upon sliding contact with a medium. Therefore, in the above conventional example, the area of exposure of this alumina film to the sliding surface is kept to a minimum so as to reduce the probability of sliding contact of this alumina film with the medium. Therefore, this alumina film does not function as a sliding protective film for sliding contact with the medium, but functions as the base film, which is part of the element-forming members, or as the protective film effective in the element-forming process.
Recently, the frequency of contact between a slider and a medium increases with a reduced flying height of the slider and also with the practical use of a contact-recording system in which a slider is always held in contact with the medium, and besides with the practical use of magneto-resistance effect elements having poor sliding durability, the enhancement of the sliding durability can not be expected even if the area of the process protective film is reduced as in the above conventional example, and there has been encountered a problem that the element portion travel surface is worn and damaged.
Therefore, a sliding protective film, constituted by a multi-layer film made of silicon, carbon and so on, has been formed on a slider travel surface, a flying rail surface and an element portion travel surface (hereinafter, the-surfaces in this direction will be referred to as xe2x80x9ctravel surfacexe2x80x9d) so as to protect these surfaces from sliding contact.
In order to achieve a high-density recording design of a magnetic disk unit, it is necessary to make the distance (this distance will hereinafter be referred to as xe2x80x9cmagnetic spacingxe2x80x9d) between the element portion travel surface and a magnetic layer of the medium very narrow. This sliding protective film is a loss for the narrowing of the magnetic spacing, and therefore the thickness of this sliding protective film has heretofore been not more than several tens of nm. However, as described above, the frequency of contact between the slider and the medium increases, and there has been encountered a problem that the sliding protective film, having the above thickness, is insufficient in durability.
Therefore, as disclosed in Japanese Patent Unexamined Publication Nos. 7-6340, 8-45022 and 8-45045, a film with a smaller thickness, made of a material having better durability, such as diamond-like carbon (DLC), has been used as a sliding protective film, but even such a material as DLC is insufficient in durability for the contact-recording system.
Generally, a sliding protective film, made of a material such as DLC, is formed or coated by a film-forming method called sputtering or CVD. In these film-forming methods, the density and durability of the formed film are enhanced in proportion to the thickness of the formed film. Particularly, in the formation of a diamond film which is the most durable, the film must undergo crystal growth, and therefore with the currently-available techniques, the practical film, having a thickness of not more than 1 xcexcm, can not be formed. Therefore, in order to further enhance the durability of the material, the thickness of the sliding protective film must be increased, which has invited a problem that this is contradictory to the narrowing of the magnetic spacing.
Further, in the formation of the diamond film, the temperature of the film, as well as the temperature of its vicinity, becomes more than 800xc2x0 C. In the conventional method in which the sliding protective film is formed after the recording-reproducing element is formed, the recording-reproducing element is destroyed by this temperature, and therefore diamond could not be used as the sliding protective film.
Japanese Patent Unexamined Publication Nos. 8-45022 and 8-45045 disclose a technique in which the sliding protective film is formed not only on the travel surface but also on a surface perpendicular to this travel surface so as to prevent corrosion and also to protect an edge portion of the slider. However, it is very difficult to form the film on the two surfaces continuous with each other in perpendicular relation to each other, and besides since the sliding protective film is present even at the element portion travel surface, there has been encountered a problem that this technique is not suitable for further narrowing the magnetic space.
In a method of producing the conventional magnetic head slider, the recording-reproducing elements are formed on a surface of a slider substrate by an ordinary film-forming method, and thereafter the substrate is cut into slider blocks by machining, and the sliding protective film is formed on the cut surface, again using the film-forming method. Therefore, this method has an increased number of process steps, and is complicated.
The above conventional technique has a problem that no consideration is given for satisfying the requirement for the narrowed magnetic spacing and the requirement for the enhanced sliding durability of the travel surface in a compatible manner while enhancing the performance to a higher level, and therefore the enhancement of the recording density for the future and the assurance of the reliability for an increase of the contact frequency resulting therefrom can not be achieved in a compatible manner.
It is an object of this invention to provide a magnetic head slider which achieves a narrowed magnetic spacing and the enhanced sliding durability of a travel surface in a compatible manner, and can be manufactured easily, and is inexpensive.
The above object is achieved by a construction in which instead of providing a sliding protective film, which covers a recording-reproducing element portion, on a travel surface of a magnetic head slider opposed to a medium, a sliding protective film is formed on any of surfaces perpendicular to the travel surface, and at least part of this sliding protective film covers that portion reaching the travel surface.
By providing this sliding protective film between a body of the magnetic head slider and a recording-reproducing element or at an inflow-side end surface of the magnetic head slider, a choice of a material for the sliding protective film is widened, and also in the latter case, an edge at the inflow end can be protected.
It is more preferred that the thickness of this sliding protective film in a direction of formation of this film be not less than 100 nm, and if at least one layer of this sliding protective film is made of diamond or diamond-like carbon, the sliding durability is further enhanced.
When forming the recording-reproducing element on a surface of a substrate defining a material of the magnetic head slider, the sliding protective film is formed in the same direction as a direction of formation of a film defining the recording-reproducing element, and by doing so, there can be provided the magnetic head slider which-can be easily-manufactured, and is inexpensive.
If the magnetic head slider of the present invention is used, the magnetic spacing can be reduced since any sliding protective film is not provided on a element portion travel surface, so that the high-density magnetic recording can be achieved.
The sliding protective film is formed in the direction perpendicular to the travel surface, and reaches the travel surface, and when the slider contacts the medium, that end surface of the sliding protective film, disposed at the travel surface, is in sliding contact therewith. This sliding protective film is hard, and has good sliding durability, and therefore reduces a contact stress on other travel surface portion than this end surface, thereby reducing damage due to wear.
Namely, the narrowing of the magnetic spacing and the enhancement of the sliding durability of the travel surface can both be achieved in a compatible manner.
By providing the sliding protective film of the present invention between the body of the magnetic head slider and the recording-reproducing element or at the inflow-side end surface of the magnetic head slider, the sliding protective film can be formed before the recording-reproducing element is formed, and therefore diamond, which requires a high temperature in a production process, can be used. When the magnetic head slider slides over the medium in contact therewith, a contact stress, acting on the edge portion of the magnetic head slider at the inflow end thereof, increases because of this frictional force, so that this portion is particularly worn. The sliding protective film of the present invention can be formed into a large thickness, and when this film is provided at the inflow-side end surface of the magnetic head slider, the edge portion at the inflow end is substantially protected, and there is no need to provide any sliding protective film on the travel surface as in the conventional construction.
Usually, the sliding protective film is formed by a film-forming technique such as sputtering and CVD. A film, formed by such a technique, has such a nature that its density and durability are enhanced in proportion to its thickness. Particularly when the thickness of the film is not less than 100 nm, its properties are markedly enhanced. The sliding protective film of the present invention exists in the direction perpendicular to the travel surface, and the film thickness does not cause a loss of the magnetic spacing, and therefore the thickness of the sliding protective film can be increased. Therefore, the sliding protective film with a thickness of not less than 100 nm, which has the better sliding durability than before, can be used. Furthermore, if the sliding protective film is made of a material, which is hard, and has good durability, such as diamond-like carbon and diamond, the above effects can be more positively achieved.
Therefore, the film of diamond-like carbon or diamond, having a thickness of not less than 1 xcexcm, which has heretofore been unable to be used, can be used.
And besides, in the magnetic head slider of the present invention, when forming the recording-reproducing element on the surface of the substrate defining the material of the magnetic head slider, the sliding protective film can be formed in the same direction as the direction of formation of the film defining the recording-reproducing element, and therefore there can be provided the magnetic head slider which greatly reduces the steps of the production process, and can be easily manufactured, and is inexpensive.